My '87 1100 came with V&H (round) system. I put the SS2R on to reduce noise and avoid unwanted attention. I used the original front sections and just got the SS2R for the first year listed for the 1100, I think it was for the '88. It fit fine but I may have made a special bracket to get it up higher than the supplied mount allowed. I'm working on a friend's thrashed '87 that has a homemade looking, 1 piece that sounds similar to the one you describe. This one is about 6" long, exits about at the passenger's foot peg and may as well be an amplifier because it is louder that some race systems. The round silencer from my old V&H system fit perfectly on this system (after cutting it just behind the collector). The only 'fabrication' required other than cutting the pipe was adding springs to keep the new rear slip-on section attached. If welding tabs on your old collector sound too difficult, just use a length of safety wire with loops on each end just long enough to be a bit wider than the system when stuffed between the pipes just ahead of the collector. Just hook the forward end of the (2) springs to the wire loop. The finished system is still louder than I prefer, but way quiter than what came on it.
Hope this was of some help.